Biological Explanations

• Genetics involve genes transmitted from parent to offspring which may impact psychological features
• The Genetic basis of schizophrenia involves family studies, candidate genes, and mutations
• Family Studies have shown that risk of schizophrenia increases in line with genetic similarity to a relative with the condition e.g. Gottesman
• Gottesman conducted a large-scale family study which showed that participants had a 2% chance of developing schizophrenia if relative is an aunt, 9% if relative is a sibling, 48% chance is relative is an identical twin
• Candidate genes show that schizophrenia is polygenic and caused by genes coding for neurotransmitters e.g. Stephen Ripke
• Stephen Ripke et.al. combined all previous data from genome-wide studies to compare the genetic make-up of schizophrenics compared to controls
• Stephen Ripke et.al found 107 separate genetic variations associated with an increased risk of schizophrenia
• Schizophrenia is aetiologically heterogenous as different combinations of factors result in the condition
• Mutations in parental DNA due to radiation/poision/viral infections may be a cause for schizophrenia e.g. Brown et.al.
• Brown et.al found positive correlations between paternal age and risk of schizophrenia (0.7% under 25, 2% over 50) which shows mutations as age is associated with sperm mutation
• The Biological Explanations for schizophrenia are Genetics and Neural Correlates
• Neural Correlates are patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience
• Neural Correlates for schizophrenia are the original dopamine hypothesis and the updated dopamine hypothesis
• The Original Dopamine Hypothesis is based on the discovery that antipsychotics used to treat schizophrenia cause symptoms similar to Parkinsons disease which is associated with low dopamine levels
• There is evidence to support the Original dopamine hypothesis e.g. Curran et.al.
• Curran et.al. found that amphetamines, which increase DA levels, worsened symptoms in people with schizophrenia and induced symptoms in people without
• Hyperdopaminergia is the condition of having too much dopamine activity
• Hypodopaminergia is the condition of having too little dopamine activity
• The Updated Dopamine Hypothesis was proposed by Kenneth Davis et.al based on the addition of cortical hypodopaminergia
• Low dopamine levels proposed in the updated dopamine hypothesis may explain negative symptoms of schizophrenia e.g. speech poverty
• There is evidence against the dopamine hypothesis e.g. McCutcheon et.al.
• McCutcheon et.al. found that post-mortem and live scanning studies have consistently found raised levels of glutamate in brain regions of schizophrenics